Solution metering apparatus

ABSTRACT

Solution metering apparatus for accurately metering and/or mixing one or more solutions in precise proportions for delivery to a solution-receiving device or process. The apparatus is provided with a source of power for filling a metering container of the apparatus with a predetermined volume of solution, and mechanism for controlling the predetermined volume.

United States Patent Howard T. Hodges, deceased [72] Inventor late of Perinton, NY. (by Claire F. Hodges, executrix) I [211 App]. No. 860,837

{22] Filed Sept. 24, 1969 [45] Patented Aug.31, 1971 [73] Assignee Eastman Kodak Company Rochester, NY.

{54] SOLUTION METERING APPARATUS 11 Claims, 10 Drawing Figs.

[52] U.S.Cl 417/148, 222/440, 222/432 [51] 1n1.Cl F04i 3/00, G0lf11/28 [50} FieldoiSearch 417/148, 101, 149; ZZZ/158,432, 440

[ 5 6] References Cited UNITED STATES PATENTS 2,141,427 12/1938 Bryant 417/148 2,889,846 6/1959 Glasby... 417/148X 3,163,174 12/1964 P1101 137/101.27 1 011121019 PATENTS 565,490 7/1957 Italy 222/158 Primary Examiner-William L. Freeh Assistant E.raminerR. E. Gluck Auorneys- Robert W. Hampton and Steve W. Gremban ABSTRACT: Solution metering apparatus for accurately metering and/or mixing one or more solutions in precise proportions for delivery to a solution-receiving device or process. The apparatus is provided with a source of power for filling a metering container of the apparatus with a predetermined volume of solution, and mechanism for controlling the predetermined volume.

INVENTOR.

FIG

AT TORNE S PATENTED AUB31 Ian sum 2 BF 4 HOWARD T. HODGESDECEASED, BY CLAIRE F. HODGES,EXECUTRIX BY M PATENIEU M183 1 I91:

SHEET 3 OF 4 HOWARD T. HODGES,DECEASED, BY CLAIRE F. HODGES,EXECUTRIX INVENTOR.

ATTORNEYS PATENTEI] M1931 Ian SHEET [1F 4 FIG.IO

FLUID PRESSURE SOURCE HOWARD T HODGESDECEASED, BY CLAIRE F HODGES,EXECUTRIX KHMQM ATTORNEYS SOLUTION METERING APPARATUS BACKGROUND or THE INVENTION This invention relates generally to metering devices, and more specifically to an improved power-operated, solution metering apparatus.

Apparatus for metering and/or mixing one or more solutions are particularly applicable to devices and chemical processes that require accurate measurement and delivery of a solution or solutions in precise quantity or proportions. In many of such applications, the metering and/or mixing of a solution or solutions in precise quantity or porportions is provided by precision manufactured pumps designed to maintain a stable pump rate for a given life. In those situations where corrosive solutions are handled, the parts of such pumps that are in direct contact with the solution must be constructed of a material that will not be chemically attached by the solution, or prone to rust or corrode. Naturally, precision pumps of this type are relatively expensive. Also, the performance of such pumps, particularly when designed for a precise flow rate, are subject to variables such as drive speed, wear which affects parts clearances, and changes in supply and output pressures. Applicant's power-operated, solution metering apparatus is believed to obviate many of the disadvantages of such prior known metering apparatus.

SUMMARY OF THE INVENTION This invention includes within its scope a power-operated, solution metering apparatus for accurately metering and/or mixing one or more solutions. Metering apparatus'of this type are useful for replenishing processing solutions in a photographic processing device, and are further useful in any chemical process utilizing mixtures of liquids or solutions. The solution metering mechanism of this invention is operated by a suitable source of motive power, and the volume of solution introduced into a metering container of the apparatus is controlled by volume limiting means coupled to the container such as a volume limiting chamber comprising a hollow flexible member, a suction cylinder, a bellows, a manometer type device, or a pressure regulating device.

One of the objects of the present invention is to provide power operated, solution metering apparatus for devices, chemical processes and the like for metering and/or mixing one or more solutions.

Another object of the invention is to provide a poweroperated, solution metering apparatus having volume limiting meansfor controlling the volume of solution introduced into a metering container of the apparatus.

Objects and advantages other than those set forth above will be apparent from the following description when read in connection with the accompanying drawings:

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a schematic view partially in section showing a preferred embodiment of the solution metering apparatus of this invention with a volume limiting chamber as the volume limiting means;

FIG. 2 is a section view of the volume limiting chamber taken along line 22 of FIG. 1;

FIG. 3 is a segmental view in section of a volume limiting chamber of the type shown in FIG. 2 showing a modification of the resilient pressure pad;

FIG. 4 is a segmental view partially in section showing another embodiment of the volume limiting chamber of FIG. 2;

FIG. 5 is a segmental view partially in section showing still another embodiment of the volume limiting means of the invention;

FIG. 6 is a schematic view similar to FIG. 1 showing another embodiment of the solution metering apparatus of this invention with a suction cylinder as the volume limiting means;

FIG. 7 is a segmental view of an alternate construction of the power cylinder for operating the suction cylinder of FIG.

FIG. 8 is a view similar to FIG. 6 showing another embodiment of the solution metering apparatus in its normal position and incorporating a manometer type volume limiting means;

FIG. 9 is a view of the apparatus of FIG. 8 showing the metering apparatus and volume limiting means in a volume limiting position; and

FIG. 10 is a view similar to FIG. 8 showing another embodiment of the solution metering apparatus in its normal position and incorporating a pressure regulating, volume limiting means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a preferred embodiment of the power-operated, solution metering apparatus of this invention is shown in FIG. I as comprising one or more metering containers 12 preferably constructed of a rigid, transparent material such as glass or plastic. Each of the containers 12 has a throat 14 at the lower end thereof provided with an opening for receiving a rubber seal 16. Any well-known means, not shown, such as a nut in engagement with threads on the periphery of throat 14, may be provided for holding seal 16 in the opening in sealing engagement therewith. The seal 16 has an opening through which one end of a supply tube 18 is inserted, and slidably adjustable in the direction of the arrows AA. A flexible supply hose 20 has one end connected to tube 18, and the opposite end thereof insertable in a supply tank 22 of solution. An output tube 24 has one end partially inserted into an opening in seal 16, and is provided with a suitable valve 26 for controlling solution flow from container 12 to any suitable solution-receiving device, not shown, such as a photographic processing device or the like.,Each container 12 is provided with a volumetric index 28 on the outer surface thereof for indicating the volume of solution in the container at any selected index mark. To meter a precise volume of solution, the operator must adjust metering tube 18 with the upper end thereof in alignment with a selected index mark on container 12. Solution is introduced into metering container 12 from supply tank 22 until the solution level in the metering container reaches a level designated B which is above the uppermost index mark on metering container l2. The excess solution in the metering container is allowed to drain back through supply tube 18 into supply tank 22, and such action will continue until the solution level in metering container 12 is at a level C equal to the top of tube 18, and represents a precise volume of solution. Upon opening of valve 26, the precise volume of solution in container is'fed by gravity to a receiving means such as a processing device or the like, not shown. 7

In the embodiment of the invention shown in FIG. I, the motive power responsible for introducing solution from supply tank 22 into metering container 12 comprises any suitable vacuum pump 30 connected to a manifold conduit 32 which is blocked (not shown) at the right end thereof when looking at FIG. 1. A volume limiting means for each container for limiting the volume of solution introduced therein comprises a chamber 34 having a tube 35 at one end connected to manifold conduit 32, and its opposite end connected by a conduit 36 to the upper end of container 12. The chamber 34 comprises a housing for receiving a bag 38 preferably constructed'of a flexible material such as impregnated cloth, neoprene, plastic, or the like. A resilient means, such as a pressure pad 40 biased by a spring 42 as seen in FIGS. 1 and 2, or a foam rubber mat 44 as seen in FIG. 3, is provided fdr returningbag 38 to its original deflated condition. The pad 40 is slidably movable within housing 34, and adjustable stops 46 are provided for limiting movement of pad 40 in one direction. It is also possible to use a flexible material such as rubber which will stretch and recover its original shape, thus obviating the need for any additional resilient pressure means. Also, the resilient pressure means may be unnecessary if, following the suction cycle during which solution is introduced into metering container 12, valve 48 in pump output tube 50 is closed, and valve 52 in tube 54 is opened so that pump 30 produces an output pressure forcing evacuation of the flexible bag 38. A vent tube 56 is connected to manifold conduit 32 at a point intermediate pump 30 and the first container 12, and is provided with suitable vent valve 58 located at the junction of vent tube 56 and manifold conduit 32. Vent valve 58 is of the two-way kind which is operable to close vent tube 56 to the atmosphere while opening vent tube 56 to manifold conduit 32 or, altematively, to open vent tube 56 to the atmosphere while closing vent tube 56 to manifold conduit 32. Furthermore, a vent tube 60 is connected to each conduit 36 at a point intermediate container 12 and chamber 34, and is provided with a vent valve 62.

When vacuum pump 30 is operated during a normal suction cycle for introducing solution into metering container 12, vacuum is applied to control chamber 34 causing bag 38 to inflate resulting in a reduction in pressure within metering container 12 to a value below the pressure in supply tank 22, in this instance below atmospheric pressure, Accordingly, atmospheric pressure operating on the solution in supply tank 22 forces solution therefrom into container 12. The chamber 34 is provided with a volume preselected so that when bag 38 inflates and fills the chamber, the metering container 12 is filled with solution to a level B which is above the level of the maximum metered volume indicated, but below the level which would result in solution being forced into bag 38. By adjusting the position of stops 46 for pressure pad 40, the level of the volume of solution introduced into container 12 may be varied.

In the operation of the vacuum-operated, solution metering apparatus of FIG. 1, the operator initially adjusts the setting of tube 18 with the top thereof in alignment with the desired volume of solution to be metered, the valve 58 is operated so that vent tube 56 is closed to the atmosphere and opened to manifold conduit 32, valve 48 is opened, the valves 26, 52, and 62 are closed and vacuum pump 30 is energized for operation through a suction cycle. The vacuum created in chamber 34 during the suction cycle causes bag 38 to expand resulting in a lowering of the pressure within container 12 and solution being forced into metering container 12 to a predetermined level above the metered volume desired. Opening of vent valve 62 allows solution in container 12 to drain back through tube 18 to a level equal to the top of the tube, which is the adjusted volume setting. The valve 26 is opened to deliver the metered volume of solution to any suitable solution receiving means.

FIG. 4 disclosed a modification of the volume limiting chamber of FIGS. 1 and 2 in which a housing 64 is provided with an expandable bellows 66 mounted therein and expandable as shown in broken lines. The bellows 66 may be constructed of a stretchable rubber having a normal closed position to which it inherently returns.

Another modification of the volume limiting chamber is disclosed in FIG. 5. In this modification, a bellows 68 is provided secured by any suitable means to the upper end of container 12. A spring 70 in the bellows 68 urges the bellows into a normally closed position as seen in FIG. 5. During operation, the spring force increases as bellows 68 expands, such force increasing until it is equal to the vacuum force. At such time, solution flow into container 12 is terminated. it is also possible to provide an adjustable stop 72 for limiting the expansion of the bellows 68 to a predetermined amount representing a finite volume of solution introduced into container 12.

In the modification of the invention disclosed in FIG. 6,

parts similar to the parts disclosed in FIGS. 1 and 2 will be denoted by the same numerals primed. ln this modification, the volume limiting means comprises a suction cylinder 74 of fixed displacement within which a piston 76 and sealing ring 78 affixed to one end of a piston rod 80 are reciprocally movable. When a vent valve 82 connected to the upper end of cylinder, 74 is closed and piston 76 moved downwardly through a section stroke from its normally inoperative position shown in full lines in FIG. 6 to its dotted position, the pressure in cylinder 74 is decreased to a value below the atmospheric pressure acting on the solution in supply tank 22'. Accordingly, solution is forced from the supply tank into metering container 12' to a predetermined level B. When valve 82 is opened, the solution in metering container 12' will flow under the influence of gravity through tube 18' back into supply tank 22' until the solution level reaches the level of tube 18', designated by C. The solution remaining in metering container 12 represents a precise volume of solution determined by the initial setting of tube 18'. Upon opening valve 26', the metered solution is fed by gravity to a receiving means such as a processing device or the like.

Any suitable power means may be provided for moving piston 76 and piston rod through its suction stroke and than back to its normal inoperative position. In FIG. 6, the power means comprises a compressed air or gas cylinder 84 of known type having a valve 86 for controlling the release of the gas, and a gauge 88 for measuring the pressure of the released gas. The gas is fed from cylinder 84 through a tube 90 to a manifold 92, the ends of which are connected to opposite ends of a power cylinder 94. The piston rod 80 extends through openings in the bottom and top of cylinders 74, 94 respectively, and a piston 96 and sealing ring 98 are mounted on the end thereof. Valves 100, 102 are provided in each of the arms of manifold 92. With valves 82, 102 closed and valve 100 opened, manually opening valve 86 introduces gas into the upper end of cylinder 94 for driving the pistons 76, 96 and piston rod 80 downwardly to provide a suction stroke for the apparatus. By closing valve 100, and opening valves 82, 102 gas pressure introduced into the lower end of cylinder 94 will return the pistons 76, 96 and piston rod 80 to this normal inoperative position as seen in FIG. 6.

In an alternate construction of the suction cylinder 74 shown in FIG. 7, a spring 104 may be provided interposed between piston 76 and cylinder 74 which is tensioned during the return of pistons 76, 96 and piston rod 80 to this normal inoperative position. When the pistons are released by venting cylinder or releasing any suitable latch means, not shown, for the pistons or piston rod, the spring 104 urges the piston 76 through a suction stroke of fixed volume. Although the spring 104 is shown interposed between piston 76 and cylinder 74, a spring may be interposed between piston 96 and cylinder 94 or between both pistons 76, 96 and cylinders 74, 94 respectively.

In the embodiment of the invention shown in FIGS. 8 and 9, parts similar to parts disclosed in FIGS. 1-4 will be denoted by the same numerals double-primed. In this embodiment of the invention, the motive power means comprises any suitable vacuum pump 30". The volume limiting means is shown as a manometer-type device comprising a cylinder 106 partially filled with a liquid, and a tube 108 parallel to cylinder 106 having one end connected by a bent section 110 to the bottom of cylinder 106 and its opposite end open. In this embodiment of the invention, operation of the vacuum pump 30" causes pressure in metering container 12" to decrease below the atmospheric pressure in supply tank 22". The increased pressure in supply tank 22" forces solution therefrom into the me tering container 12". During such action, the pressure in the upper end of cylinder 106 is also decreased below atmospheric, and atmospheric pressure acting on the liquid in tube 108 forces the liquid from tube 108 into cylinder 106. When all of the liquid in tube 108 is forced into cylinder 106 as best seen in FIG. 9, an air bypass is formed in which air bubbles through the liquid in cylinder 106 into the upper end of the cylinder in an attempt to equalize the pressure differential. As a result of this bypass, further solution flow into metering container 12" from supply tank 22" is stopped. At that point, the solution level in container 12" will be at some level such as D (FIG. 9) above the maximum metered volume indicated. This condition will persist as long as vacuum pump 30" continues to operate. Upon turning off the vacuum pump, solution in container 12" will drain back through tube 18" until the solution reaches level C" equal to the top of the tube which is the precise volume of solution that is to be metered. The liquid in cylinder 106 returns into tube 108 where it seeks the same level in both as shown in FlG. 8. Opening valve 26" delivers the metered volume of solution to a suitable solution receiving means.

1n the embodiment of the invention shown in H6. 10, parts similar to parts disclosed in F168. 1-4 will be denoted by the same numerals tripled-primed. In this embodiment of the invention, the motive power means comprises any suitable fluid pressure source 112 such as a container of compressed air or the like shown schematically in block diagram form. The fluid pressure source 112 is connected by a tube 114 and a tube 118 of manifold 116 to the inside of supply tank 22 through a seal 120 to subject the solution therein to a positive pressure. The metering container 12 on the right when looking at FIG. is provided with a supply hose 20" connected by a tube 122 to the bottom thereof, and the container 12 on the left is provided with the normal supply tube 18" which is slidably adjustable within container 12" for controlling the quantity of solution to be metered as described in connection with previous embodiments. The upper end of each of the metering containers 12" is provided with a seal 124 for slidably supporting a tube 126 open at each end and vertically adjustable within the container for, among other things, controlling the quantity of solution to be metered in those situations where an adjustable supply tube 18" is not provided for the metering container. Since the volume of solution in tube 126 is extremely small in comparison to the metered quantity, the error in metering volume is negligible. As solution enters a metering container 12" and reaches the lower open end of tube 126, the container is no longer vented and solution rises in tube 126 to a pint where the pressure of the supported column of solution in the tube equals the air or gas pressure supplied to supply tank 22", whereupon further solution flow to container 12" is discontinued.

The solution volume limiting means for this embodiment comprises the aforementioned vertically adjustable tube 126 in combination with a pressure regulating means for regulating the fluid pressure supplied to supply tank 22", and hence the height of the solution column in tube 126. The pressure regulating means comprises a vertical column of liquid in an open ended cylinder 128. A curved tube 130 has one end insertable within cylinder 128 and its opposite end connected by a flexible hose 132 to tube 114 and fluid pressure source 112 to permit vertical adjustment of tube 130 within cylinder 128 for regulating the fluid pressure supplied to tank 22" in a manner to be explained hereinafter.

in the operation of this embodiment of the invention when a valve 13a in tube 114 is opened, fluid pressure forces solution from supply tanks 22" into metering containers 12", and simultaneously forces liquid out of tube 130 into cylinder 128, the liquid level within tube 130 and cylinder 128 initially being at the same level as seen in F 16. 10. As the pressure builds up, the level of liquid in tube 123 continues to move downwardly until all of the liquid has traveled from tube 130 into cylinder 128. At this pressure, detennined by the selected height between the initial level of the solution in cylinder 128 designated F and the open end of tube 130 designated G, air will pass from the end of tube 130 into cylinder 128 and provide a bypass preventing further pressure build up. During this action, the solution in metering containers 12" enters tube 126 and rises therein to a predetermined level designated H. At this level, the pressure of the column of solution in tube 126 is equal to the regulated air pressure supplied to tank 22", preventing any further solution flow into containers 12". This level may be adjusted to any desired level by raising or lowering tube 130 in cylinder 128, thereby changing the distance between the initial level F of the solution in cylinder 128 and the end G of the tube 130, and hence the value of air pressure supplied to tank 22.

Any liquid may be used in the pressure regulating means, and a liquid having a low evaporation rate such as transformer oil or the like is preferred. Also, any suitable commercial pressure limiting valve could be substituted for cylinder 128 and tube 130 of the pressure regulating means. A valve 134 can be turned off and exit valve 135 opened to permit the solution within the metering container 12" on the right as seen in FIG. 10 to flow to a processing device or the like. The solution within the left container 12" that is above the level of metering tube 18" is returned to supply tank upon opening of a vent valve 136. The solution remaining in metering container 12" represents the precise volume of solution which may be fed by gravity to a receiving means, such as a processing device or the like, upon opening of exit valve 26".

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be un derstood that variations and modifications can be effected within the spirit and scope of the invention.

' Iclaim:

1. in a solution metering apparatus, the combination comprising:

a solution supply tank;

a solution metering container;

means for interconnecting said solution supply tank and said solution metering container for hydraulic communication therebetween so that said solution metering container can receive solution from said solution supply tank;

vacuum source means cooperable with said solution metering container for drawing solution from said solution supply tank into said solution metering container;

means cooperable with said vacuum source means for limiting, to a predetermined volume, solution drawn into said solution metering container from said solution supply tank by said vacuum source means; and

conduit means for interconnecting said solution metering container, said vacuum source means and said solution limiting means so that a vacuum can be effected therebetween.

2. The combination as recited in claim 1, wherein said solution limiting means includes:

a chamber having a predetermined volume, said chamber being connected to said vacuum source means for pneumatic communication therewith; and

an expandable hollow member located in said chamber, said expandable member being connected to said solution metering container for pneumatic communication therewith and being movable between deflated and inflated posi tions,

whereby said vacuum source means is adapted to move s expandable member from said deflated position to s inflated position for drawing solution from said solution supply tank into said solution metering container,

3. The combination as recited in claim 2, wherein said solution limiting means further includes:

resilient pressure means disposed in said chamber and in contact with said expandable member for urging said expandable member for movement from said inflated position to said deflated position.

4. The combination as recited in claim 3, wherein said solution limiting means further includes:

adjustable means for selectively restricting expansion of said expandable member from said deflated position for varying the volume of solution drawn into said solution metering container from said solution supply tank by said vacuum source means.

5. The combination as recited in claim 2, wherein said expandable member is a bellows, said bellows being integrally connected to said solution metering container and having resilient means in contact therewith for urging said bellows for movement from said inflated position to said deflated position.

6. The combination as recited in claim 1, wherein said soiution limiting means includes:

pressure responsive mean sfs aid pressure responsive means having a first portion connected to said vacuum source means and said solution metering container for pneumatic communication respectively therewith and having a second portion exposed to ambient pressure,

whereby a pressure differential can be established between said first and second portions of said pressure responsive means.

7. The combination as recited in claim 1, wherein said solution limiting means includes:

a closed, vertically disposed first vessel partially filled with a liquid, said first vessel having a first cross-sectional area and having upper and lower portions, said upper portion of said first vessel being connected to said vacuum source means and said solution metering container for pneu- 1 matic communication respectively therewith;

a vertically disposed second vessel having a second crosssectional area smaller than said first cross-sectional area of said first vessel and having upper and lower portions, said upper portion of said second vessel being open to expose the interior of said second vessel to ambient pressure; and

means for interconnecting said lower portion of said first vessel and said lower portion of said second vessel for. hydraulic communication between said first and second vessels. I

8. In a solution metering apparatus, the

prising:

a solution supply tank;

a solution metering container;

means for interconnecting said solution supply tank and said solution metering container for hydraulic communication therebetween;

vacuum source means cooperable with said solution metering container for drawing solution from said solution supply tank into said solution metering container;

conduit means for interconnecting said vacuum source ,means and said solution metering container so that a vacuum can be effected therebetween; and

combination commeans interposed in said conduit means between said vacuum source means and said solution metering container for limiting, to a predetermined volume, solution drawn into said solution metering container by said vacuum source means.

9. The combination as recited in claim 8, wherein said solu tion limiting means includes: 1

a chamber having apredetermined volume, said chamber being connected to said vacuum source means for pneumatic communication therewith; and

an expandable hollow member confined in said chamber, said expandable member being connected to said solution metering container for pneumatic communication therewith and being movable between deflated and inflated positions,

whereby said vacuum source means is adapted to move said expandable member from said deflated position to said inflated position for drawing a predetermined volume of solution from said solution supply tank into said solution metering container.

10. The combination as recited in claim 8, further comprising:

means connected to said solution metering container for reducing, to a selected volume, a predetermined volume of solution drawn into said solution metering container by said vacuum source means; and

means connected to said solution metering container for delivering a selected volume of solution from said solution metering container.

11. The combination as recited in claim 10, wherein said solution reducing means includes:

means for supporting said solution metering container above said solution sugply tank; means for mounting sai solution supply tank and solution metering container interconnecting means for movement within said solution metering container between a plurality of discrete elevational levels; and

means for venting the interior of said solution metering container to ambient pressure. 

1. In a solution metering apparatus, the combination comprising: a solution supply tank; a solution metering container; means for interconnecting said solution supply tank and said solution metering container for hydraulic communication therebetween so that said solution metering container can receive solution from said solution supply tank; vacuum source means cooperable with said solution metering container for drawing solution from said solution supply tank into said solution metering container; means cooperable with said vacuum source means for limiting, to a predetermined volume, solution drawn into said solution metering container from said solution supply tank by said vacuum source means; and conduit means for interconnecting said solution metering container, said vacuum source means and said solution limiting means so that a vacuum can be effected therebetween.
 2. The combination as recited in claim 1, wherein said solution limiting means includes: a chamBer having a predetermined volume, said chamber being connected to said vacuum source means for pneumatic communication therewith; and an expandable hollow member located in said chamber, said expandable member being connected to said solution metering container for pneumatic communication therewith and being movable between deflated and inflated positions, whereby said vacuum source means is adapted to move said expandable member from said deflated position to said inflated position for drawing solution from said solution supply tank into said solution metering container.
 3. The combination as recited in claim 2, wherein said solution limiting means further includes: resilient pressure means disposed in said chamber and in contact with said expandable member for urging said expandable member for movement from said inflated position to said deflated position.
 4. The combination as recited in claim 3, wherein said solution limiting means further includes: adjustable means for selectively restricting expansion of said expandable member from said deflated position for varying the volume of solution drawn into said solution metering container from said solution supply tank by said vacuum source means.
 5. The combination as recited in claim 2, wherein said expandable member is a bellows, said bellows being integrally connected to said solution metering container and having resilient means in contact therewith for urging said bellows for movement from said inflated position to said deflated position.
 6. The combination as recited in claim 1, wherein said solution limiting means includes: pressure responsive means, said pressure responsive means having a first portion connected to said vacuum source means and said solution metering container for pneumatic communication respectively therewith and having a second portion exposed to ambient pressure, whereby a pressure differential can be established between said first and second portions of said pressure responsive means.
 7. The combination as recited in claim 1, wherein said solution limiting means includes: a closed, vertically disposed first vessel partially filled with a liquid, said first vessel having a first cross-sectional area and having upper and lower portions, said upper portion of said first vessel being connected to said vacuum source means and said solution metering container for pneumatic communication respectively therewith; a vertically disposed second vessel having a second cross-sectional area smaller than said first cross-sectional area of said first vessel and having upper and lower portions, said upper portion of saId second vessel being open to expose the interior of said second vessel to ambient pressure; and means for interconnecting said lower portion of said first vessel and said lower portion of said second vessel for hydraulic communication between said first and second vessels.
 8. In a solution metering apparatus, the combination comprising: a solution supply tank; a solution metering container; means for interconnecting said solution supply tank and said solution metering container for hydraulic communication therebetween; vacuum source means cooperable with said solution metering container for drawing solution from said solution supply tank into said solution metering container; conduit means for interconnecting said vacuum source means and said solution metering container so that a vacuum can be effected therebetween; and means interposed in said conduit means between said vacuum source means and said solution metering container for limiting, to a predetermined volume, solution drawn into said solution metering container by said vacuum source means.
 9. The combination as recited in claim 8, wherein said solution limiting means includes: a chamber having a predetermined volume, said chamber being connected to said vacuum source means for pneumatic communication therewith; and an expandable holloW member confined in said chamber, said expandable member being connected to said solution metering container for pneumatic communication therewith and being movable between deflated and inflated positions, whereby said vacuum source means is adapted to move said expandable member from said deflated position to said inflated position for drawing a predetermined volume of solution from said solution supply tank into said solution metering container.
 10. The combination as recited in claim 8, further comprising: means connected to said solution metering container for reducing, to a selected volume, a predetermined volume of solution drawn into said solution metering container by said vacuum source means; and means connected to said solution metering container for delivering a selected volume of solution from said solution metering container.
 11. The combination as recited in claim 10, wherein said solution reducing means includes: means for supporting said solution metering container above said solution supply tank; means for mounting said solution supply tank and solution metering container interconnecting means for movement within said solution metering container between a plurality of discrete elevational levels; and means for venting the interior of said solution metering container to ambient pressure. 